JPH0359505B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a signal separation method for separating mutually interleaved correlated signals and uncorrelated signals.
More specifically, correlated signals that are interleaved with each other, that is, a signal that has a correlation that can be identified with the signal contents of adjacent signal sections, such as a video signal, and uncorrelated signals, that is, the signal contents of adjacent signal sections. The purpose of this invention is to provide a new signal separation method that can separate signals that have no correlation that can be equated to PCM audio signals, for example, PCM audio signals. BACKGROUND TECHNOLOGY AND PROBLEMS There is a demand for video tape recorders, especially home video tape recorders, to lower the tape running speed in order to lengthen the recording time of one tape cassette. If the speed is slowed down, the relative speed of the audio head with respect to the audio track formed at the side edge of the video tape will naturally be slowed down, resulting in a problem of poor sound quality. On the other hand, there is also a demand for so-called high-fidelity (HiFi) audio for home video tape recorders. Therefore, there was a need to develop a technology that could improve the sound quality even when the tape running speed was slow. Therefore, instead of adopting a method of providing an audio track at the side edge of the video tape, an attempt was made to record the PCM audio signal on an audio track parallel to the video track that is oblique to the longitudinal direction of the video tape. was done. However, this results in a signal format that cannot be reproduced by a conventional video tape recorder. The present invention was made in the course of research aimed at improving the sound quality in a signal format that can be played back on a conventional video tape recorder. Purpose of the Invention The present invention provides a novel signal separation method for separating correlated signals and uncorrelated signals that are interleaved with each other, thereby realizing signal transmission in which correlated signals and uncorrelated signals are interleaved with each other and transmitted. It attempts to make it possible. Structure of the Invention In order to achieve the above object, the signal separation method of the present invention generates a signal in which correlated signals that are correlated in adjacent signal sections and digital uncorrelated signals that are uncorrelated in adjacent signal sections are interleaved. A signal separation method that separates the interleaved signals by removing the uncorrelated digital signal in the start section of each operation cycle having a period several times the signal section, or by removing the uncorrelated digital signal in the next signal section. The signal is input to a signal separation circuit so as to be the same as a digital signal, and is output from the signal separation circuit using a delay circuit provided inside the signal separation circuit that has a delay time of one signal section. A signal is created by delaying the correlation signal or the signal input to the signal separation circuit by one signal period, and the signal input to the signal separation circuit and the signal output from the delay circuit are combined in the signal period next to the start period. A non-correlated signal is obtained through arithmetic processing, and at the same time a correlated signal is obtained by arithmetic processing of the non-correlated signal and the signal input to the separation circuit, and then in each signal section up to the final section of the operation cycle. By performing arithmetic processing on the correlated signal output from the signal separation circuit and delayed by one signal period by the delay circuit and the signal input to the signal separation circuit, a non-correlated signal is obtained, and at the same time, the non-correlated signal and The present invention is characterized in that a correlation signal is obtained by performing arithmetic processing on the signal input to the separation circuit, and the above-described series of operations is repeated. Embodiment FIGS. 1 to 5 are for explaining an example of implementation of the signal separation method of the present invention, and FIG. 1 shows an encoder circuit of a video tape recorder using the present invention. The encoder circuit separates the NTSC composite video signal into a carrier chrominance signal and a luminance signal, frequency-converts the carrier chrominance signal to a low-frequency conversion chrominance signal, and interleaves the luminance signal with a carrier audio signal, which will be described later. , the interleaved signal is frequency modulated, and the above-mentioned color signal is mixed with the mutually interleaved luminance signal and carrier audio signal, and the mixed signal is transmitted to the video head. In FIG. 1, 1 is a comb filter that separates the NTSC composite video signal Ycom into a luminance signal _Y and a carrier color signal _C3.58 , and 2 is a carrier color signal C output from the comb filter 1. _{3. 58} (carrier frequency is 3.58MHz) to low frequency conversion color signal C ₆₈₈ (carrier frequency is 688KHz) Color low speed conversion circuit 3 is the low frequency conversion circuit output from color low frequency conversion circuit 2 A recording amplifier amplifies the converted color signal C ₆₈₈ so as to obtain an optimum recording current. 4 is a synthesis circuit that interleaves the luminance signal Y output from the comb filter 1 and a carrier audio signal Alr, which will be described later. 5 is a combination circuit. The signal output from 4
FM modulation circuit that performs FM modulation, 6 a recording amplifier that amplifies the signal output from the FM modulation circuit 5 so as to obtain an optimum recording current, 7 superimposes the signals output from the two recording amplifiers 3 and 6 on each other. It is an adder that 8 is a PCM encoder that performs PCM modulation on the audio signal A, and 9 is a quadrature two-phase modulation circuit that performs quadrature two-phase modulation on the left and right channel audio signals output from the PCM encoder 8. 10 and 11 are low pass filters (LPFs) that pass the left and right channel audio signals output from the PCM encoder 8; 12 and 13 are L signal modulators that perform carrier suppression amplitude modulation on the audio subcarriers using the left and right channel audio signals; It is a signal modulator, and the audio signals Al and Ar output from the PCM encoder 8 are passed through low pass filters (LPF) 10 and 11 to the L signal modulator 1.
2 and 13. Reference numeral 14 denotes an oscillator for generating a carrier wave, which generates a signal with a frequency expressed by the formula 0.5fh (2n+1) (where fh: horizontal scanning frequency [15.75 KHz], n: integer). The reason why the oscillation frequency of this oscillator 14 is set to 0.5fh (2n+1) will be explained later. 15 is a synchronizing signal generator that receives the output signal of the oscillator 14 and sends a burst flag signal to the burst generator 16; the burst generator 16 receives the burst flag signal and the output signal of the oscillator 14 and generates an audio overburst signal B; do. This audio overburst signal B is generated at a timing such that it is superimposed on the horizontal synchronization signal (by the way,
In the NTSC system, the color burst signal is superimposed on the back porch of the horizontal sync signal). A -57° phase shifter 17 delays the phase of the signal output from the oscillator 14 by 57°, and the signal output from the phase shifter 17 is input to the L signal modulator 12 as an audio subcarrier. 18 is a −90° phase shifter 18 that delays the phase of the signal output from the phase shifter 17 by 90°.
The signal output from the phase shifter 17 is input to the R signal modulator 13 as an audio subcarrier. Thus, in the modulation circuit 9, two audio subcarriers having a phase difference of 90 degrees from each other are subjected to carrier suppression amplitude modulation by the PCM modulated left and right audio signals. The signals Al and Ar subjected to carrier suppression amplitude modulation in this way are added together in the synthesis circuit 4 to produce a carrier audio signal.
This carrier audio signal Alr is frequency interleaved with the luminance signal Y output from the comb filter 1. Further, the audio overburst signal B is superimposed on the horizontal synchronization signal of the luminance signal Y. The quadrature two-phase modulation for obtaining such a carrier audio signal is an application of the quadrature two-phase modulation method for obtaining one carrier color signal from two color difference signals. However, it is not always necessary to perform quadrature two-phase modulation on the two carrier audio signals, but it is possible to make the frequency bands of the two carrier audio signals different and separate the left and right audio signals from each other using a filter when demodulating. Also good. The output signal of the synthesis circuit 4 is frequency modulated in the FM modulation circuit 5, appropriately amplified in the recording amplifier 6, superimposed on the low-frequency converted color signal C ₆₈₈ outputted from the recording amplifier 6, and sent to the video head. and magnetically recorded on the video track of the videotape. Next, the frequency of the sub-audio carrier wave of the carrier audio signal interleaved with the luminance signal Y will be explained with reference to FIGS. 2 and 3. Figure 2 shows the energy distribution of the luminance signal Y. The energy of the luminance signal Y is concentrated at frequencies that are integral multiples of fh (15.75KHz), and there is a large amount of energy between each energy distribution region. A frequency range with no or almost no frequency is created. The center frequency of each frequency region in which the energy of the luminance signal Y is not distributed is expressed as 0.5fh (2n+1). Therefore, the frequency of the sub audio carrier wave is set to 0.5fh (2n+
1), it is possible to prevent the carrier audio signal Alr and the luminance signal Y from interfering with each other as shown in FIG. This frequency interleaving is performed in general television broadcasting between the luminance signal Y and the carrier color signal (shown by the broken line in Figure 2.By the way, the frequency of the color subcarrier is
It is 3.58MHz. ) is an application of frequency interleaving. Figure 3a shows an example in which the carrier audio signal Alr is distributed in a relatively low band of the luminance signal Y, and Figure 3b shows an example in which the carrier audio signal Alr is distributed in a relatively low band of the luminance signal Y. Figure c shows an example in which the carrier audio signal Alr is distributed from the high range of the band of the luminance signal Y to the outside of the band. In the case shown in FIG. 3a, the interference between the luminance signal Y and the carrier audio signal Alr is greater than in the cases shown in FIGS. 3b and 3c. On the other hand, in the case shown in FIG. 3C, interference is minimized, but the band of the frequency interleaved signal is widened. Figure 3b
In the case shown in FIG. 3, the interference is greater than in the case shown in FIG. 13C, but the interference is smaller than in the case shown in FIG. Examples of interleaving between a luminance signal and a carrier audio signal are shown in FIGS. 3a to 3c, but how to perform frequency interleaving is a design issue. FIG. 4 shows a decoder circuit. In the figure, 19 is a reproduction amplifier that amplifies the reproduction signal from the video head, 20 is a low-pass filter (LDF) for obtaining a low-frequency conversion signal C ₆₈₈ , and 21 is a luminance signal Y and a luminance signal Y interleaved with each other. This is a high pass filter (HPF) for obtaining the carrier audio signal Alr. The low frequency conversion color signal C ₆₈₈ that has passed through the low pass filter (LPF) 20 is input to the low color conversion circuit 22, where it is time-base compensated and becomes a carrier color signal C ₃ having a frequency of 3.68MHz. ₆₈ frequency converted. This converted color signal C ₃ . ₆₈ is input to the synthesis circuit 23 where it is added to the luminance signal Y, and the synthesis circuit 23 outputs a composite video signal Ycom. The composite video signal Ycom is processed in an image reproduction circuit (not shown). The signals output from the high-pass filter 21 (luminance signal Y and carrier audio signal Afr interleaved with each other) are demodulated in the FM demodulation circuit 24. 25 is a separation circuit that separates the luminance signal Y and carrier audio signal Alr which are interleaved with each other. The circuit configuration and operation of the separation circuit 25 will be explained in detail later. The luminance signal Y output from the separation circuit 25 is sent to a synthesis circuit 23, where it is added to the carrier color signal C ₃ . ₆₈ . on the other hand,
Carrier audio signal output from separation circuit 25
Alr is synchronously detected by the audio synchronous detection circuit 26. Next, the configuration and operation of the audio synchronous detection circuit 26 will be explained. 27 is a bandpass filter (BPF) that passes the carrier audio signal Alr output from the separation circuit 25; 28 is an L signal synchronous detector that detects the left channel audio signal; and 29 is an R signal that detects the right channel audio signal. Synchronous detector, 30 and 31 are L signal synchronous detector 2
8. A low-pass filter (LPF) that passes the audio signal (PCMized) output from the R signal synchronous detector 29.
The audio signals of the left and right channels output from this low pass filter (LPF) 30, 31
The signal is sent to the PCM decoder 32 via the PCM decoder 32. Then, the audio signal is PCM demodulated by the PCM decoder 32 and reproduced by an audio reproduction circuit (not shown). Reference numeral 33 denotes a burst extracting circuit for extracting the audio overburst signal B from the luminance signal Y. The audio overburst signal B extracted by the burst extracting circuit 33 is input to the phase comparator 34. The phase comparator 34 compares the phases of the audio burst signal B and the reference subcarrier output from the voltage controlled oscillator 35, sends the phase comparison signal to the voltage controlled oscillator 35, and outputs the reference subcarrier output from the voltage controlled oscillator 35. Synchronize with carrier audio overburst signal B. This voltage controlled oscillator 3
The reference subcarrier output from the L signal synchronous detector 28 is used for synchronous detection of the left channel audio signal input to the L signal synchronous detector 28. 36 has a phase lower than that of the reference subcarrier output from the voltage controlled oscillator 35.
A -90° phase shifter is used to obtain a reference subcarrier delayed by 90°, and the reference subcarrier output from the phase shifter 36 is input to an R signal synchronous detector 29 for synchronous detection of the right channel audio signal. used for. FIG. 5 shows the circuit configuration of a separation circuit 25 that separates the luminance signal Y and carrier audio signal Alr which are interleaved with each other. In the figure, 37 is the first adder, and the separation circuit 25
A first inverter 38 that inverts the input signal (Y+Alr) to the input signal (Y+Alr) and the output signal of the second adder inputted via the switching circuit described later into a negative signal.
The output signal of this adder 37 is added to the output signal of the adder 37 as a luminance signal Y to the synthesis circuit 23.
etc., and is also input to the delay circuit 39 in the separation circuit 25. The delay circuit 39 receives the luminance signal Y
The signal output from the delay circuit 39 is delayed by 1H by one horizontal period of the television.
The signal is inverted by the inverter 40 into a negative signal.
A second adder 41 adds the input signal (Y+Alr) to the separation circuit 25 and the output signal of the second inverter 40. The output signal of the second adder 41 is sent to the audio synchronous detection circuit 26 as a carrier audio signal Alr, and is also input to the first inverter 38 via the switching circuit 42. The switching circuit 42 outputs a switching signal.
Controlled by Ssw, the first horizontal scanning period Th ₀ of each operation cycle whose period is m (an integer greater than or equal to 1) + 1 times the horizontal period is in the off state, and the other period in each operation cycle is in the on state, That is, the state in which the carrier audio signal Alr is sent to the first inverter 38 is maintained. The operation of this separation circuit 25 in one operation cycle will be explained below. (1) First, the switching circuit 42 is turned off during the first horizontal scanning period _th0 of each operation cycle. It is necessary that only the luminance signal Y is input to the separation circuit 25 during this horizontal scanning period. If the luminance signal during the horizontal scanning period is Y ₀ , the luminance signal is output from the separation circuit 25.
Only Yo is output, and carrier audio signal Alr is not output. (2) When entering the next horizontal scanning period _Th1 , the switching circuit 42 turns on (it remains on for m horizontal periods thereafter). The signal input during this horizontal scanning period Th ₁ is assumed to be Y ₁ +Alr ₁ . During this horizontal scanning period Th ₁ , the delay circuit 39 outputs the luminance signal Y ₀ that was input to the separation circuit 25 during the previous horizontal scanning period Th ₀ , and the luminance signal Y ₀ is sent to the second inverter 40 . Therefore, it is inverted to a negative number and input to the second adder 41. The second adder 41
performs a process of adding -Y ₀ to the input signal Y ₁ +Alr ₁ . By the way, the luminance signal Y has correlation,
In other words, since the signal content in one horizontal scanning period and the signal content in the next horizontal scanning period are similar enough to be considered the same, the luminance signals Y ₁ and Y ₀ are equal. It can be considered as Therefore, the adder 41 outputs only the carrier audio signal Alr ₁ . Further, this carrier audio signal Alr ₁ passes through the switching circuit 42, is inverted by the first inverter 38, and is input to the first adder 37. The adder 37 performs a process of adding -Alr to Y ₁ +Alr ₁ and outputs a luminance signal Y ₁ . (3) If the signal input to the separation circuit 25 in the next horizontal scanning period Th ₂ is Y ₂ +Alr ₂ , then in this horizontal scanning period Th ₀ the luminance signal Y ₁ is input from the delay circuit 39.
is output, a signal -Y ₁ is sent from the second inverter 40 to the second adder 41, and the adder 41
In this step, a process of adding −Y ₁ to Y ₂ +Alr ₂ is performed. Since Y ₂ and Y ₁ can be considered to be the same, the adder 41 outputs the carrier audio signal Alr ₂ . Further, this carrier audio signal Alr ₂ is inverted to a negative number and sent to the first adder 3.
8, the first adder 38 outputs the luminance signal Y ₂ . This operation is repeated thereafter. And Ym+
One operation cycle is completed when Alrm is input and this signal is separated into Ym and Alrm. Then, the next operation cycle is repeated in the same manner as described above. Table 1 below shows signal changes for the input signal Y+Alr, the output signal of the delay circuit 39, and the two output signals Y and Alr of the separation circuit 25 in order to make it easier to understand the operation of the separation circuit 25. It is something. In Table 1, for convenience, the carrier audio signal is indicated by "A" instead of "Alr".
Further, IHDL indicates the output signal of the delay circuit 39. In Table 1, one operation cycle is up to the horizontal scanning period in which the input signal Ym+Am is input, and the next operation cycle begins from the horizontal scanning period in which the input signal Ym+o is input.

[Table] Note that the Th ₀ switching circuit 42 is turned off during the first horizontal scanning period for each operation cycle whose period is m+1 times the horizontal period, and the supply of the carrier audio signal Alr to the separation circuit 25 is stopped during that period. To be stopped, the correlation of the luminance signal is 100%
This is because it is not. That is, there is a slight difference between the signals of two adjacent horizontal scanning periods, and this difference causes an error in the arithmetic processing for separation by the separation circuit 25. If the arithmetic processing is continued while ignoring the existence of the difference, the difference will accumulate and the error will gradually increase. Therefore, after a certain period of time, that is, m+1 times the horizontal period, the calculation is started again in the initial state in order to prevent the error at that time from being carried into the calculation of the next operation cycle. . By the way, the value of m may be always constant or may be changed depending on the content of the image. In order to keep the value of m constant, for example, a ring counter that counts horizontal synchronizing signals may be used to generate the switching signal Ssw, and the switching circuit 42 may be controlled using this signal. Furthermore, in this case, the ring counter can be used to create a signal that prohibits the generation of the carrier audio signal Alr, and the supply of the carrier audio signal Alr to the separation circuit 25 for one horizontal scanning period is prohibited for each operation cycle. By doing so, signal separation by the separation circuit 25 can be realized. In addition, when changing the value of m according to the content of the image, detect the line correlation by an appropriate means, and increase m when horizontally scanning a part of the image with high line correlation. It is conceivable to reduce m when horizontally scanning a low part. Another Embodiment FIG. 6 shows a separation circuit 25a used in another embodiment of the invention. In the figure, 43 is a first switching circuit, and the interleaved input signal Y+Alr is connected to the switching terminal (normally open) which is electrically connected to the common terminal when receiving a switching signal among its two switching terminals. The other switching terminal, that is, the switching terminal that is electrically connected to the common terminal when not receiving a switching signal (normally closed) receives an output signal from a second adder, which will be described later. A common terminal of the first switching circuit 43 is connected to an input terminal of a delay circuit 44.
The switching circuit 43 receives the switching signal during the first horizontal scanning period Th ₀ in each operation cycle, and receives the signal Y ₀ + input to the separation circuit 25a.
The state in which A ₁ is sent to the delay circuit 44 is maintained, but from the next horizontal scanning period Th ₁ to the m-th horizontal scanning period
No switching signal is received until the second
The output signal of the adder (more on this later)
The state in which the signal is sent to the delay circuit 44 is maintained. Thereafter, such an operation is repeated at a period m+1 times the horizontal period. The delay circuit 44 delays the signal output from the switching circuit 43 by one horizontal period (IH), and the signal delayed by the delay circuit 44 is inverted to a negative number by the first inverter 45. and is input to the first adder 46. The first adder 46 receives the signal Y+ input to the separation circuit 25a.
This is to add Alr and the output signal of the first inverter 45. 47 is an attenuator that halves the value of the output signal of the first adder 35, and 48 is a second switching circuit that divides the output signal of the first adder 35 and the output signal of the attenuator 36 into two. Outputs the signal corresponding to the content of the switching signal. Specifically, when receiving a switching signal, the switching terminal electrically connected to the common terminal (normally open) receives the output signal of the attenuator 47, and the other switching terminal, that is, the switching terminal The (normally closed) switching terminal connected to the common terminal when not receiving a signal receives the output signal of the first adder 46. The switching circuit 48 receives the switching signal during the horizontal scanning period Th ₁ (the horizontal scanning period following the first horizontal scanning period Th ₀ after the start of each operation cycle), and enters a state in which it outputs the output signal of the attenuator 47. However, after that, the mth horizontal scanning period Thm
It does not receive a switching signal until the end of the first horizontal scanning period Thm+ ₀ in the next operation cycle, and continues to send out the output signal of the first adder 46. The second switching circuit 48 operates for a time m+1 times the horizontal period (Th ₀ ~
The above-mentioned operation is repeated with a cycle of thm). 49 is a second inverter that negatively inverts the signal output from the second switching circuit 48;
The output signal of the inverter 49 is input to the second adder 50. The second adder 50 is a separation circuit 25a.
The signal Y+Alr is the carrier audio signal input to
A signal -Alr, which is a negative version of Alr, is added, and the output signal is sent out as a luminance signal Y to the outside of the separation circuit 25a. Further, the output signal of the second adder 50 is sent to the second switching circuit 4 as described above.
It is also input to the normally closed switching terminal No. 8. Next, the operation of this separation circuit 25a will be explained. (1) First, during the first horizontal scanning period Th ₀ , Y ₀ + ₁ is input to the separation circuit 25a. The carrier audio signal ₁ of this input signal is a signal obtained by inverting the carrier audio signal Alr ₁ component of the signal input in the next horizontal scanning period _th1 . When this separation circuit 25a is used, the separation circuit _25a is
It is necessary to process the signal in a circuit on the preceding stage than the separation circuit 25a so that the carrier audio signal inputted to _{5a is an inverted version of the carrier audio signal Alr 1 inputted} in the next horizontal scanning period Th1. There is. During this first horizontal scanning period Th ₀ , the first switching circuit 43 receives the switching signal and transmits the input signal Y _{0 +1} to the delay circuit 44 .
What is output as the luminance signal Y during this period is the luminance signal or synchronization signal in the last horizontal scanning period of the previous operation cycle. (2) During the next horizontal scanning period Th _1, the first switching circuit 43 does not receive the switching signal, and the second switching circuit 43 does not receive the switching signal.
The second switching circuit 48 transmits the output signal of the adder 50 to the delay circuit 44, while the second switching circuit 48 uses the output signal of the attenuator 47 as the carrier audio signal Alr to the second inverter 49 and the separation circuit 25a. It is ready to be sent to the outside. In this horizontal scanning period Th ₁ , the delay circuit 44 sends the signal to the separation circuit 2 in the previous horizontal scanning period Th ₀ .
The signal Y ₀ + ₁ input to 5a is input to the inverter 45
is inverted and input to the first adder 46. The adder 46 adds Y ₁ +Alr ₁ input during this horizontal scanning period Th ₁ and the output signal -Y ₀ +Alr ₁ of the inverter 45, and outputs 2Alr ₁ .
Note that, as in the case of the previous embodiment, Y ₁ and Y ₀ can be considered to be substantially the same from the correlation of the luminance signal Y. The output signal 2Alr ₁ of the second adder 46 is input to an attenuator 47 and is attenuated to Alr ₁ by the attenuator 47 . The output signal Alr ₁ of the attenuator 47 is output as a carrier audio signal to the outside of the separation circuit 25a through the second switching circuit 48, and is inverted by the second inverter 49 and sent to the second adder 50. is input. The adder 5
0 is the separation circuit 25a during this horizontal scanning period _Th1.
Y ₁ + _{Alr 1 inputted} to
The signal Y ₁ is sent to the outside of the separation circuit 25 a as a luminance signal, and the signal Y ₁ is also sent to the delay circuit 44 via the first switching circuit 43 . (3) In the next horizontal scanning period Th _{2 ,} the second switching circuit 48 switches to a state in which it sends out the output signal from the first adder 46 . This horizontal scanning period
In Th ₂ , the luminance signal Y ₁ output from the second adder 50 in the previous horizontal scanning period Th ₁ is output from the 1H delay circuit 44, and the inverted signal Y ₁ of the luminance signal Y 1 is added to the first addition signal Y ₁ . 46. The adder 46 is connected to the separation circuit ₂ during this horizontal scanning period Th2.
-Y ₁ is added to the signal Y ₂ +Alr ₂ inputted to 5a, and the resulting signal Alr ₂ is sent to the second switching circuit 48. Therefore, the signal
Alr ₂ is used as a carrier audio signal in the separation circuit 25
It is sent to the outside from a. Also, this signal Alr ₂
is inverted by the second inverter 49 and becomes the second
is input to the adder 50. The adder 50 is
A process of adding -Alr ₂ to Y ₂ +Alr ₂ is performed, and the signal Y ₂ is sent to the outside of the separation circuit 25a as a luminance signal, and is also sent to the first switching circuit 43.
The signal Y ₂ is also sent to the delay circuit 44 via
Send out. Thereafter, the above procedure is repeated until the mth horizontal scanning period.
The same operation described in (3) is repeated. Table 2 below
In order to make it easier to understand the operation of the separation circuit 25a of the present invention, the input signal Y+Alr, the output signal of the delay circuit 44, and the two output signals Y and
This figure shows the signal changes in one operation cycle for Alr. In Table 2, for convenience, the carrier audio signal is indicated by "A" instead of "Alr", and 1HDL is indicated by 1H delay circuit 4.
The output signal of 4 is shown.

[Table] As mentioned above, separation circuit 25 or 2
By using 5a, it is possible to separate correlated signals and uncorrelated signals that are frequency interleaved with each other. Therefore, it becomes possible to frequency-interleave and transmit an audio signal that has no correlation with a luminance signal, which is a correlated signal. Therefore, in a helical scanning home video tape recorder, an audio signal can be recorded along with a video signal by a video head on a video track diagonal to the longitudinal direction of the video tape, and a conventional audio head can record the edge of the video tape. Compared to a method of recording sound on an audio track formed parallel to the longitudinal direction of the head, the relative speed of the head to the track can be increased. Therefore, high fidelity audio reproduction (HiFi) can be achieved in the video tape recorder. In addition, since the audio signal is frequency interleaved with the luminance signal, even if the resulting signal contains both a luminance signal and an audio signal, the frequency band is the same as that of the luminance signal, or the frequency band is slightly different from that of the luminance signal. It is possible to prevent the frequency band from becoming unnecessarily wide. Images recorded using frequency interleaving in this way can be played back by conventional video tape recorders, and even if such a signal multiplexing method is adopted, compatibility with conventional video tape recorders cannot be achieved. It is possible to maintain The signal separation method of the present invention can be applied not only to the separation of signals in which a luminance signal and a carrier audio signal are interleaved, but also to the separation of signals in which correlated signals and uncorrelated signals are frequency interleaved. . However, in order to smoothly carry out the arithmetic processing for separation, the uncorrelated signal needs to be a digital signal that is an intermittent signal rather than an analog signal that is input continuously. Effects of the Invention As stated above, the signal separation method of the present invention has the following effects:
A signal separation method that separates a signal obtained by interleaving a correlated signal that is correlated in adjacent signal sections and a digital uncorrelated signal that is not correlated in adjacent signal sections, the interleaved signal being The uncorrelated digital signal in the start section of each operation cycle, which has a period several times the period of the signal section, is removed or made to be the same as the digital signal in the next signal section, and then input to the signal separation circuit. The signal separation circuit delays the correlation signal output from the signal separation circuit or the signal input to the signal separation circuit by one signal period using a delay circuit provided inside the signal separation circuit and having a delay time of one signal period. A non-correlated signal is obtained by processing the signal input to the signal separation circuit and the signal output from the delay circuit in the signal period following the start period, and at the same time obtains the non-correlated signal. A correlated signal is obtained by performing arithmetic processing on the signal input to the separation circuit, and thereafter, in each signal period up to the final period of the operation cycle, the delay circuit output from the signal separation circuit delays the signal by one signal period. A non-correlated signal is obtained by arithmetic processing of the correlated signal and a signal input to the signal separation circuit, and at the same time, a non-correlated signal is obtained by arithmetic processing of the non-correlated signal and the signal input to the separation circuit. The present invention is characterized in that the operation of obtaining a correlation signal is performed, and the above-described series of operations is repeated. Therefore, according to the signal separation method of the present invention, it is possible to separate a correlated signal and an uncorrelated digital signal into frequency interleaved signals into a correlated signal and an uncorrelated digital signal. Become. Therefore, it is possible to transmit signals using a transmission method that transmits signals by frequency interleaving a correlated signal and an uncorrelated digital signal. Alternatively, it becomes possible to perform multiplex transmission without unnecessarily widening the range. When the present invention is particularly applied to a helical scanning video tape recorder, uncorrelated audio signals are added to correlated luminance signals.
By converting to PCM and frequency interleaving, it becomes possible to record the audio signal on the video track of the videotape. Therefore, when it comes to audio, the relative speed of the head to the track is much faster than when using a conventional video tape recorder that records audio signals on an audio track parallel to the longitudinal direction of the video tape, making it difficult to reproduce audio. can achieve very high fidelity.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an encoder circuit of a video tape recorder implementing the signal separation method of the present invention, FIG. 2 is a diagram showing the energy distribution of a luminance signal, and FIGS. FIG. 4 shows the energy distribution of different examples of frequency interleaving of a carrier audio signal (an uncorrelated digital signal) with a carrier audio signal (an uncorrelated signal); FIG. A block diagram showing one example, and FIGS. 5 and 6 are circuit diagrams showing different examples of signal separation circuits used to implement the signal separation method of the present invention. Explanation of symbols, 25, 25a...Signal separation circuit, 3
9, 44...Delay circuit.

Claims (1)

[Claims] 1 A signal separation method that separates a signal in which correlated signals that are correlated in adjacent signal sections and digital uncorrelated signals that are uncorrelated in adjacent signal sections are interleaved, and the interleaved signal is , the signal separation circuit removes the uncorrelated digital signal in the start section of each operation cycle having a period several times the period of the signal section, or makes it the same as the digital signal in the next signal section. The correlation signal output from the signal separation circuit or the signal input to the signal separation circuit is divided into one signal period by using a delay circuit provided inside the signal separation circuit and having a delay time of one signal period. By creating a delayed signal and processing the signal input to the signal separation circuit and the signal output from the delay circuit in the signal section following the start section, a decorrelated signal is obtained and at the same time the decorrelation is performed. A correlation signal is obtained by processing the signal and the signal input to the separation circuit, and is then outputted from the signal separation circuit in each signal section up to the final section of the operation cycle, and is processed by the delay circuit for one signal section. A non-correlated signal is obtained by processing the delayed correlated signal and the signal input to the signal separation circuit, and at the same time, by processing the non-correlated signal and the signal input to the separation circuit. A signal separation method characterized in that the above-described series of operations is repeated.